Internal spa filter

ABSTRACT

An internal spa filter for a spa, having a filter body with an inlet opening at its one end and a discharge orifice at its opposite end, the sides of such body are formed with auxiliary spa water inlet openings. The filter also includes a filter bag having a sheath encompassing the exterior of the filter body and a pocket extending inwardly from the front end of the sheath into the filter body from the main spa water inlet opening. Operation of the spa water circulation system draws spa water into the main spa water inlet opening through the filter bag pocket into the filter body while concurrently spa water is drawn transversely through the filter bag sheath and auxiliary spa water openings into the filter body, all of such spa water flows rearwardly out of the filter body through the filter body discharge orifice.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to filters for liquids. Moreparticularly, the present invention is directed to an internal filterfor use in the water circulation systems of conventional pools or spas.

[0003] 2. Description of the Prior Art

[0004] Filters of various configurations are known in the art for use inswimming pools, spas, and the like in order to remove solid particlesand debris from the circulated water. Such filters are typically mountedin-line within the pool or spa circulation system and are configuredwith a liquid-permeable filter media such that when the circulationsystem is in operation, the water can be pulled through the filter andpumped back into the pool or spa, leaving the captured debris on thefilter for subsequent removal.

[0005] The conventional cartridge filter as is known and used in the artis generally comprised of a cylindrical filter element having one ormore layers or sheets of a porous material configured with a pore sizeto allow the passage of water while trapping and removing the solidparticles from the water that are unable to pass through the pores. Asthe filter traps more and more solid particles, the pores in the filtermedia become clogged, inhibiting the flow of water through the pool orspa's circulation system and thereby decreasing performance and possiblyeven damaging the circulation pump. In an attempt to address theseconcerns, the cartridge filters known in the art typically employrelatively large sheets of the porous filter material that are pleatedso as to provide an increased filter surface area, thus increasing thelife and performance of the filter, while not increasing the filter'soverall size. The filter material is maintained in its cylindrical,pleated configuration by being mounted on a rigid cylindrical core andcapped on each end by an annular end cap.

[0006] Though the conventional cartridge filter is in wide use, thereare still several shortcomings with this filter type that have not yetbeen overcome. First, the flow rate through the cartridge filter islimited by the material and configuration of the pleats and theapertures in the rigid cylindrical core. Such flow rate is typically onthe order of 100 gpm when the filter is new. Second, despite the overallincreased surface area of the filter material achieved by the pleats,only so much of this surface area is truly usable, as the folds of thepleat are tight and are butted up against the cylindrical core.Moreover, as particles and debris become lodged between the pleats, theuseful filter surface area that is lost is effectively doubled becausethe particles and debris clog pores on both adjacent surfaces of thepleat. Thus, cartridge filters become clogged and experience decreasedflow rates relatively quickly. A third shortcoming of the cartridgefilters known and used in the art is that they cannot be readily cleanedafter becoming clogged. In the interest of increasing the total filtersurface area, the pleats of the typical cartridge filter are numerousand densely configured about the filter's circumference. Thus, in orderto remove the debris trapped deep within the pleat folds, high pressurereverse flow or meticulous debris removal using a vacuum or manualtechnique between each pleat is necessary. It is further recommendedthat the cartridge be soaked overnight in a cartridge cleaning solutionand then be thoroughly cleaned a second time before being returned touse. Because of these inconveniences, some pool and spa owners simplyuse their cartridge filters until they become clogged and discard them,often prematurely, rather than bothering to clean them out. Moreover,because cartridge filters trap debris on the outside of the filter only,when the filter is removed from the pool or spa for cleaning ordisposal, it is possible that the debris that is loose and easilyremoved will fall off the filter into the clean side of the circulationsystem rather than being permanently removed.

[0007] For these reasons, other pool and spa filters have been proposedin the art. Diatomaceous earth (“DE”) filters house internal, parallelgrids made of extremely fine mesh that is coated with DE, which iscrushed, petrified bone that acts as an adhesive and traps particles anddebris from the water as it is filtered through the layers of DE grids.These DE filters are relatively more expensive than comparable cartridgefilters and may be subject to municipal or environmental authorityregulations pertaining to cleaning and disposal. Similarly, sand filtershave also been proposed that essentially use a sand and gravel filtermedium that mixes with the circulated water as it passes through thefilter to pull out dirt and debris. However, the debris is notpermanently captured by the sand filter medium and can eventually workits way through the filter and back into the pool or spa circulationsystem. It has been proposed that an additional solution be added to thesand to coagulate the particles and debris being filtered into largerclumps that can be more easily trapped by the sand filter medium. As afurther maintenance step with sand filters, periodically, the sanditself is depleted from the filter and more sand of a specific type mustbe added. Sand filters, like the DE filters, are more costly thancartridge filters.

[0008] Bag-type filters for separation of unwanted solids from liquidprocess flows have also been employed in various industrial filtrationapplications in the interest of increasing flow rate and efficiency. Tothis end, filter assemblies having bag filters supported on rigidstructures or stiffening frames and having elaborate sealingarrangements between the filter and the surrounding housing have beenproposed. For example, U.S. Pat. No. 4,769,052 to Kowalski is directedto a flexible fabric filter bag apparatus having multiple supportsurfaces. A double-walled, porous cylinder cooperates with a stretchingframe to suspend and support the filter bag within a rigid cylindricalouter housing. An annular flange is provided in the housing's inner walland is configured to sealingly engage a metal ring within the bag's openend when the bag, the double-walled cylinder, and the stretching frameare positioned inside the outer housing. A cover is installed over theopen end of the outer housing to seal the filter and to force thestretching frame downwardly to draw the filter bag taut against thesurfaces of the double-walled support cylinder.

[0009] U.S. Pat. No. 5,910,247 to Outterside is directed to a similarfilter bag system. Like the Kowalski filter apparatus, Outtersidediscloses essentially a double-walled filter support cylinder,consisting of an outer basket and an inner tubular member, a housinghaving a lid for sealing the filter, and a filter bag having a ring inits open end to sealingly engage a flange on the basket. Outtersidefurther discloses specific dimensions for the filter bag whichpurportedly maximize the surface area without restricting the processflow rate. Moreover, the Outterside system's supporting structures areconfigured to prevent collapse of the filter bag when the process flowis reversed to backwash and clean the filter without removing it. Hence,it is essential that the filter bag fit snugly and securely over theouter basket and inner tubular member. To this end, Outterside disclosesthat the filter body is smaller in diameter than the outside diameter ofthe tubular support member so that the filter must be stretched to fitover the tubular body and is retained thereon through a frictional fit.

[0010] Therefore, the bag filters known and used in the prior artessentially entail a multi-walled support structure that may furtherinclude additional stretching or stiffening frames, a filter bag that issecured on the support structure and shaped by the alternative frames,and a filter housing, or vessel, that contains the filter bag assemblyand provides for a positive seal between the “dirty” and “clean” side ofthe filter along a ring integral to the bag's open end. Based on theconfiguration and number of components in these prior art industrialbag-type filters, it follows that such filters are not well-suited foruse in spas because of their complex design and inherent relatively highcost. Furthermore, the housing, which plays a critical role in thefunction and performance of the prior art bag-type filters, isparticularly ill-suited for use in a spa's circulation system becausethe conventional spa's filter-receiving cavity cannot accommodate thehousing, and the housing itself, having only one small inletstrategically positioned above the location where the filter is sealedwithin the housing, would likely perform poorly under the changing waterlevels and other conditions of a pool or spa during use.

[0011] Thus, there exists a need for an inexpensive, convenient, andfunctionally efficient filter for use in spas and the like that is botheasily reusable and disposable.

SUMMARY OF THE INVENTION

[0012] The present invention is directed to an internal spa filterincluding a filter body and a complementary filter bag having a sheathwhich encompasses the exterior of the filter body and an internal pocketwhich extends into the filter body. The filter body is configured to beinstalled within a spa's water circulation system in order to filterparticles and debris out of the water. As the spa water is circulated,through the filter body a vortex effect is created within the filter bagpocket trapping debris therein for later removal without the risk of thedebris falling off the filter and back into the spa water. Theconfiguration and materials of the spa filter of the present invention,as compared to the prior art filters, provide for much higher flow ratesthrough the filter, further enhancing both the performance and life ofthe pump of the spa circulation system. Moreover, the spa filter of thepresent invention is relatively inexpensive to manufacture, whereby,after prolonged use, the filter bag itself may be either readily cleanedand reused or alternatively simply discarded.

[0013] The filter body of the spa filter of the present invention isdefined by a cylinder having a spa water opening at its inlet end and aspa water discharge orifice at its opposite end. Throughout the filterbody's cylindrical wall is formed, a pattern of auxiliary spa waterinlet openings. The inlet and auxiliary openings permit the passage ofthe circulated spa water from the outside of the filter body to theinside thereof. The sheath of the filter bag is joined to the pocketthereof along a circumferential inseam. Accordingly, when the bag isplaced about the filter body, the closed end of the pocket is insertedwithin the filter body's open end while the sheath encompasses theoutside surface of the filter body's cylindrical wall, with the inseamof the filter bag positioned substantially along the inlet edge of thecylindrical wall's inlet end to maintain the position of the filter bagon the supporting filter body. The pocket extends towards the dischargeend of the filter body.

[0014] One embodiment of the filter body utilizes a cylinder, the sidesof which are formed with a pattern of round through-hole openingspreferably having a nominal diameter of 0.60″. For a cylinder having anoutside diameter of approximately 5½ and a length of approximately 8″,sixteen such holes are radially-spaced apart in each of six parallel,circumferential rows in the wall to yield a total of ninety-six throughholes generally spaced uniformly throughout the wall. In an alternativefilter body embodiment, a mesh-type pattern is formed in the cylindersidewall having a pattern of small, square apertures throughout the wallarranged in spaced-apart relationship about parallel circumferentialrows substantially throughout the wall. Because the square apertures arerelatively smaller than the through-hole apertures of the firstembodiment, for the same overall dimensions of the wall, the number ofsquare apertures and the number of rows are significantly increased,yielding a total of more than two-thousand square apertures. A thirdembodiment of the filter body of the present invention has lengthwiseaxially extending slots formed about its circumference.

[0015] In each embodiment of the filter body, the body includes an openinlet end about which the filter bag sheath is draped and an oppositerear closed discharge end formed by a rear wall integral with the rearend of the filter body and generally normal to the axis of the filterbody. A central circular discharge orifice is provided in the wall fordischarge of the flow of the spa water entering the filter body throughthe filter bag. A length of tubing extends from the discharge orificenormal to the rear wall and projecting axially away from the filterbody. The tubing is configured with external threads for threadablyengaging piping of the spa's circulation system. Preferably, the filterbody will be positioned vertically within a filer-receiving bag of thespa with the inlet end of the cylinder disposed above the discharge endthereof so that water from the tub of the spa is drawn downwardlythrough the filter body to the suction end of the spa's pump. The filterbody may be constructed of a thermoplastic material such as polyethylene(PE), polypropylene (PP), polyvinyl chloride (PVC), or acrylonitrilebutadiene styrene (ABS). These materials are readily available, arerelatively inexpensive, and are easily processed using injection moldingand finishing techniques known in the art.

[0016] The filter bag of the present invention includes a support ringat the juncture of the sheath and pocket along a circumferential inseamformed by looping the upper end of the pocket over the upper end of thesheath to form a loop or circumferential cavity. The support ringpreferably has a nominal diameter substantially equivalent to thenominal diameter of the filter body so as to be positioned adjacent theupper end of the filter body when the filter bag is placed on the filterbody, thereby maintaining the filter bag in position and keeping thepocket open during use. To this end, the support ring is to beconstructed of any suitable rigid or semi-rigid material such as athermoplastic material or stainless steel. To maintain the position ofthe support ring within the circumferential cavity and to secure theinseam, stitching, welding, stapling or other fabric attachment meansknown in the art are employed.

[0017] A removal handle spans the open upper end of the filter bagpocket and is attached at two opposite locations. The handle may bestitched, welded, or otherwise joined to the filter bag using anyattaching means known in the art, but is preferably attached within theinseam itself. The length of the handle is sufficient to loosely spanthe pocket opening, so that the handle may droop within the pocket whennot in use and may be pulled up for convenient access when the handle isto be grasped to remove the filter bag from the filter body.

[0018] The filter bag of the present invention may be constructed of adurable, porous, fibrous material known in the art for use in variousfiltration applications. Though many types of fabrics may be used influid filtration to effectively remove debris and particulate matterwhile allowing the fluid itself to pass through the filter media, in apreferred embodiment, the material selected will have a porosity ratingof 40 to 50 microns and have a weight on the order of 12 oz/yd².Examples of suitable materials include polypropylene (PP), polyethylene(PE), polyester felt, or fiberglass. The handle may be made of the samematerial as the sheath and the pocket or may be made of a conventionalcotton and polyester textile material.

[0019] In operation, after the sheath of the filter bag has beenremovably positioned in covering relationship over the filter body withthe bag pocket extending into the filter body, the internal spa filterof the present invention is ready for use and is installed within thefilter-receiving bay of a conventional spa with the filter in directcommunication with the spa's circulation system on the suction side ofthe pump. Once the spa tub is filled with water and the circulationsystem is operated, the water is drawn through the filter by the pump.Because the inlet opening of the filter bag, approximately 5½ diameter,is relatively larger than the discharge orifice at the closed end of thefilter body, which is typically on the order of 1½, this difference inarea will naturally create a vortex tending to draw the water downthrough the filter pocket, pulling larger debris into the pocket andtrapping it there for later removal. The vortex action and the resultingstrong suction of water through the filter also creates a vacuumpressure on the inside of the filter that serves to pull the filterbag's sheath tightly against the exterior of the filter body, thuseffectively creating a tight fit between the sheath and the filter bodywhich causes all water being pulled through the filter to pass throughthe filter bag.

[0020] The porosity of the filter bag material, the configuration of theopen pocket, and the vortex effect cooperate to provide for higher flowrates through the filter (on the order of about 150 gallons per minute)as compared to conventional prior art spa filters. This increased flowrate translates to enhanced performance of the spa in terms of therelaxation and therapeutic benefits to the user and the life of thecirculation pump.

[0021] When the filter bag of the present invention has becomesufficiently dirty that it should be cleaned or replaced, the spa'scirculation system is shut down and the filter bag is simply lifted outof the filter body by grasping the handle. The debris trapped by thefilter during use will remain within the inside pocket, thereby notcontaminating the spa water as the filter bag is removed from thefilter-receiving bay. If the filter bag is removed from the spa to becleaned for reuse, the bag is dumped or rinsed out to remove all debristhat has been trapped or alternatively may be washed or laundered in aconventional washing machine and dryer to more thoroughly clean andsanitize the bag. If it is preferred that the filter bag be replacedrather than being cleaned, the used filter bag may be simply discardedand a new bag put into the filter body. Because the materials andconstruction methods employed in producing the filter of the presentinvention are relatively inexpensive, disposing of the filter bag isboth a convenient and economical it cleaning the bag.

[0022] Other features and advantages of the invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, which illustrate, by way of example, thefeatures of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a cut-away perspective view of an internal spa filterembodying the present invention showing the filter bag positioned on thecylindrical filter body;

[0024]FIG. 2 is a perspective view of the filter body shown in FIG. 1;

[0025]FIG. 3 is a broken perspective view of the discharge end of thefilter body shown in FIG. 1;

[0026]FIG. 4 is a perspective view of a first alternative embodiment ofthe filter body;

[0027]FIG. 5 is a perspective view of a second alternative embodiment ofthe filter body;

[0028]FIG. 6 is a cut away perspective view of the filter bag shown inFIG. 1;

[0029]FIG. 7 is a cut-away perspective view of the filter bag positionedupon the filter body of FIGS. 1, 2, and 3;

[0030]FIG. 8 is a vertical sectional view taken along line 8-8 of FIG.7;

[0031]FIG. 9 is a perspective view of an internal spa filter of thepresent invention installed within a spa's filter-receiving bay.

[0032]FIG. 10 is a cut-away perspective view of said internal spa filterduring operation of the spa's water circulation system;

[0033]FIG. 11 is a vertical sectional view showing the operation of avortex created during operation of the spa's water circulation system;and

[0034]FIG. 12 is a broken sectional view showing a filter bag beingremoved from a spa's filter-receiving bay.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0035] As shown in the drawings for purpose of illustration, an internalspa filter of the present invention utilizes a filter bag removablydisposed upon a cylindrical filter body and configured to be installedwithin a spa's circulation system in order to filter particles anddebris out of the spa water. While the spa filter embodying the presentinvention is described and depicted as being used in a conventional spa,it will be appreciated that the invention can also be used inconjunction with above- and below-ground swimming pools, hot tubs,Jacuzzis, or with any other system involving recirculated water that isto be filtered.

[0036] More particularly, referring to FIG. 1, a preferred embodiment ofan internal spa filter F of the present invention includes a cylindricalfilter body FB and a filter bag B having a cylindrical sheath 20 and apocket 22 that extends concentrically inwardly from the inlet end of thesheath. The upper end of the cylinder 24 of the filter body is open todefine an inlet opening 26 for spa water drawn downwardly through thecylinder by the pump 28 of the spa's water circulation system (FIG. 9).The lower end of the cylinder 24 is closed by a bottom wall 30 centrallyformed with a discharge orifice 32 (FIG. 3). The sidewalls 34 ofcylinder 24 are formed with auxiliary spa water openings in the form ofholes 36 that admit spa water that is drawn into cylinder 24 throughsheath 20 of the filter bag. In the use of the internal spa filter F allspa water being circulated through the filter will pass through and befiltered by the filter bag. Moreover, the discharge orifice 32 issmaller in area than the inlet opening 26 so that a vortex 37 is createdduring circulation of the spa water which traps debris in the pocket 22for later removal as indicated by the arrows in (FIGS. 10 and 11). Ahandle 38 is provided on the filter bag to permit the bag to beconveniently lifted from the filter body for cleaning or replacement.

[0037] A short tube 40 coaxial with the discharge opening 32 extendsdownwardly away from cylinder end wall 30 to form a water connectionmeans between discharge orifice and the suction end of pump 28 (FIG. 9)of the spa's water circulation system. The tube 40 is formed withthreads 42 for threadably engaging piping 44 connected to pump 28. Apreferred conventional thread size is 1.50 mps with a major threaddiameter of approximately 1.90″. This thread configuration accommodatesa bore 64 through the tubing 60, and thus a circular opening size, ofabout 1½″.

[0038] With continued reference to FIG. 2, the holes 66 are round andpreferably have a nominal diameter of about 0.60″. In this sameembodiment, sixteen such holes are radially-spaced apart in each of sixparallel, circumferential rows in the cylinder 24 to yield a total ofninety-six through holes generally spread uniformly throughout the wallof the cylinder sidewall. It will be appreciated that the cylinder maybe of a variety of lengths and diameters and that as the overalldimensions of the cylinder change, the pattern of holes may changeaccordingly in order to maintain a generally uniform distribution of theholes throughout the wall of the cylinder. In the embodiment shown inFIG. 2, the cylinder is configured with a nominal outside diameter of 5½and a length of 8″, as is typical in the art of spa filters, permittinga filter of the present invention to be capable of use with the majorityof spas currently on the market.

[0039] The filter body FB may be constructed from a number of differentwater-resistant materials known in the art. A preferred material is athermoplastic such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), or acrylonitrile butadiene styrene (ABS). It will beappreciated that these materials are readily available, are relativelyinexpensive, and are easily processed using injection molding andfinished techniques known in the art. Because the filter body isconfigured to be one integral unit, the injection molding process isboth effective and efficient in this application. In an alternativeembodiment, the threaded tubing 40 may be formed separately through amolding or machining operation and bonded or welded to the filter bodyin a secondary operation.

[0040] Referring now to FIG. 4, an alternative embodiment of filter bodyFB′ of the present invention, utilizes a cylinder 46 having a pattern ofauxiliary water openings in the form of small apertures 48 formedthroughout the wall of the cylinder to define a mesh-type construction.Preferably the apertures will be square shaped. Apertures 48 arearranged in spaced-apart relationship about parallel circumferentialrows substantially throughout the wall of cylinder 24′, but, because theapertures are relatively smaller than the through-holes 36, the numberof apertures and the number of rows are significantly increased. Thus,in one such embodiment, a cylinder 24′ having a 5½ nominal outsidediameter and an 8″ length is configured with thirty-three rows ofsixty-nine ⅛″ apertures each and, thus, has a total of 2,277 aperturesin the tubular wall. It will be appreciated that though the number ofapertures is significantly increased over the number of through-holes inthe filter body FB of FIG. 2, the total area for throughput of fluidfrom the outside of the filter body to the inside is not necessarilyincreased commensurately, but is, however, increased significantly. Forexample, in the exemplary embodiments disclosed, the total throughputarea for the ninety-six through-holes (FIG. 2) is 27.1 in² as comparedto a total throughput area for the 2,277 apertures (FIG. 3) of 35.6 in².As with the filter body FB, the mesh filter body FB′ includes a flatwall 30′ formed with a discharge orifice 32′. A central,externally-threaded tube 40′ extends from wall 30′ for engaging thespa's circulation system. The front of cylinder 24′ defines a spa waterinlet opening 26′.

[0041] With reference now to FIG. 4, there is shown a third embodimentof a filter body FB″ of the present invention. Filter body FB′ utilizesa cylinder 24″ having auxiliary spa water openings in the form oflengthwise rectangular slots 52 formed about its sidewall. Slots 52 aredefined by lengthwise, radially spaced-apart ribs 54 which extend alongthe wall of the cylinder. As with both the filter body FB andaforedescribed mesh filter body FB′, the ribbed filter body FB″ includesan inlet opening 26′ and an integral bottom wall 30″. Bottom wall 30′ isformed with a central circular discharge orifice 32″ from which extendsan integral threaded tubing 56 for engaging piping 40″ of thecirculation system of a spa.

[0042] In the embodiment of the ribbed filter body FB″, shown in FIG. 5,the nominal outside diameter of the cylinder is approximately 5½″ andthe overall length is approximately 8″, just as for the aforedescribedfilter body FB and the mesh filter body FB′. Twelve lengthwise ribs 54may be spaced evenly about the circumference of the filter body atsubstantially 30-degree intervals, with each rib having a radial widthof about 0.125″. In this embodiment, the total throughput area for thetwelve slots 52 is about 110 in², a significant increase over thethroughput areas for both the filter bodies FB and FB′. The effect ofthe throughput surface areas of the various embodiments on theperformance of the internal spa filter under use is explained below.

[0043] Referring now to FIGS. 6, 7, and 8, the filter bag F of thepresent invention includes a generally tubular outside sheath 20attached to a generally conical inside pocket 22 along a circumferentialinseam 60. The sheath has an upper inlet end 62 and a lower, dischargeend 64, while the pocket has an upper end 66 continuous with the upperend of the sheath, and a lower end 68. The inseam 60 is formed by theunion of the sheath and pocket along their respective upper ends. Thelower end 68 of the pocket is stitched, welded, or otherwise formedclosed to provide a radiused tip at the bottom of the generallyconically shaped cavity 70.

[0044] Preferably in the filter bag F of the present invention, both thesheath 20 and the pocket 22 are constructed of a durable, porous,fibrous material known in the art for use in various filtrationapplications. It will be appreciated that many types of fabrics may beused in fluid filtration to effectively remove debris and particulatematter while allowing the fluid itself to freely pass through the filtermedia. In a preferred embodiment, the material selected will have aporosity rating of about 40 to 50 microns. Such a material wouldtypically have a weight on the order of 12 oz/yd². Examples of suitablematerials include polypropylene (PP), polyethylene (PE), polyester felt,or fiberglass. Polypropylene is preferred, particularly for itslongevity as compared to other similar fabrics.

[0045] The arcuate shaped handle 38 spans the open upper end 61 of thepocket 22 and is attached to the filter bag 20 at the inseam 60.Opposite first and second handle ends are attached at the inseam atapproximately 180 degrees apart, on opposite sides of the sheath andpocket. The handle may be stitched, welded, or otherwise joined to thefilter bag using any attaching means known in the art. The length of thehandle is to be sufficient to loosely span the pocket opening, so thatthe handle may droop within the pocket when not in use and may be pulledup for convenient access when the handle is to be grasped to remove thefilter bag from the filter body. The handle may be made of the samematerial as the sheath and the pocket or may be made of a conventionalcotton and polyester textile material known for its durability, minimalshrinkage and wide range of uses.

[0046] Referring now to FIGS. 7 and 8, the inseam 60 is formed bylooping the upper edge of the pocket over the upper end of the sheath sothat the upper end of the pocket is substantially turned back on itself180 degrees to contact both the inside and outside surfaces of the uppersheath end. In a preferred embodiment, sufficient clearance is leftbetween the upper sheath end and the looped portion of the upper pocketend to form a loop or circumferential cavity 70 about the inseam 60.Disposed within the circumferential cavity is a support ring 72 of acircular cross-section. The support ring preferably has a nominaldiameter substantially equivalent to the nominal diameter of the filterbody so as to seat on the top end of the filter body when the filter bagis placed on the filter body, thereby maintaining the filter bag inposition on the filter body and keeping the upper end of the pocket openduring use. The support ring 72 is constructed of any suitable rigid orsemi-rigid material such as a thermoplastic or stainless steel. Beyondthe mechanical attributes of the support ring, the selected materialmust be water and corrosion-resistant. To maintain the position of thesupport ring 72 within the circumferential cavity 70 and to secure theinseam 60, a double-stitch 74 may be employed. As shown in FIG. 8, thestitch is to pass below the circumferential cavity through the outside,looped portion of the upper pocket end, through the upper sheath end,and then through the inside portion of the upper pocket end to hold theinseam together. It will be appreciated that the inseam may also besecured by other stitch configurations, welding, stapling or otherfabric attachment means known in the art.

[0047] Referring now to FIG. 1, in preparing an internal spa filter F ofthe present invention for use, the filter bag FB is positioned on thefilter body by sliding the lower sheath end 30 over the top end of thefilter body until the top inseam 60 is substantially aligned with thetop end of the filter body. In order for the filter bag to have a loosebut functional fit on the filter body, the inside diameter of the sheath22 is to be at least 0.100″ larger than the outside diameter of thefilter body, but no more than 0.300″ larger, which would create aclearance of at least 0.050″ between the filter bag and the filter bodyabout the circumference. Thus, for example, in the embodiment of thefilter body having a nominal outside diameter of 5½″, the insidediameter of the filter bag sheath would be at least 5.600″. In order forthe filter bag to be in covering relationship about the outside surfaceof the filter body, the overall axial length of the sheath is preferablysubstantially equivalent to the axial length of the filter body'scylinder. In this way, when the filter bag is advanced as far aspossible along the filter body and the inseam adjacent filter body's topend, the discharge end 64 of the sheath will be substantially adjacentthe filter body's bottom end.

[0048] With continued reference to FIG. 11, at the same time that thefilter bag's sheath 20 is slidably advanced along the outside surface ofthe filter body cylinder 24, the pocket 22 is inserted through thefilter body's inlet opening 26. The overall length of the pocket ispreferably configured such that when the filter bag is operationallypositioned on the filter body, the pocket's bottom end is substantiallyadjacent to the discharge orifice 32. In this way, the available surfacearea of the filter bag 20 for filtration is maximized without riskingocclusion of the opening at the filter body's discharge end.

[0049] Referring now to FIG. 9, the water circulation system includes apump 28 and discharge jets 80 interconnected by piping 44 disposed inthe spa tub 81. A recessed, filter receiving bay 82 is formed in a wall84 of the spa. After the filter bag B has been positioned in coveringrelationship over the filter body of FIG. 1, 4 or 5, the internal spafilter of the present invention is ready to be positioned within the bay82. As described above, the filter body is an externally-threaded tube40 which is connected to piping 44 upstream of the suction end of pump28 so as to dispose the filter F in communication with the spa's watercirculation system. Preferably the filter F is arranged vertically onthe floor 83 of the filter receiving bay in a water-tight fashion withrespect to such bay. Once installed, the door 86 of the filter-receivingbay is closed over the opening to the bay in order to protect users ofthe spa from inadvertent contact with the filter.

[0050] In the use of the aforedescribed internal spa filter, the firststep is to fill the tub 81 with water (not shown). In the conventionalspas known in the art, the filter-receiving bay 82 and the filter Fitself are configured such that when the spa tub is filledappropriately, the entire filter is submerged, with the top of thefilter typically being at least two inches below the surface of thewater. As the internal spa filter F of the present invention isconfigured to replace the conventional spa filters known in the art, itwill be appreciated that it, too, will be located beneath the surface ofthe water in the spa. Once the spa tub is filled, the pump 28 isoperated so as to circulate the water within the circulation system. Thepump has an inlet (suction) side 88 and an outlet (discharge) side 90,so that the water is pumped through the system in one direction asindicated by the arrow 92.

[0051] In operation, the water contained in the spa's tub 81 firstpasses through inlet windows 94 in the filter-receiving bay door 86. Thewindows are positioned in the door such that when the door is closed andthe spa is properly filled with water, the water level should fallbetween the top and bottom edges of the windows. It will be appreciatedthat in this way, larger debris that typically floats on the surface ofthe water such as leaves, twigs, hair, insects, etc., will be able tofloat through the windows and into the filter-receiving bay 82. Thewater is then drawn downwardly through the filter F by the pump 28.Because the inlet opening 26 of the filter body at its upper end, isrelatively larger than the discharge opening 32 at the closed bottom endof the filter body the filter pocket 22 as shown in FIGS. 10 and 11. Itwill be appreciated by those skilled in the art that because the waterlevel in the spa is above the top edge of the filter and the largerdebris that typically floats on the water can pass through the windowsin the filter-receiving bay door, the vortex action within the filterpulls the larger debris 96 into the pocket and traps it there for laterremoval.

[0052] The vortex action and the resulting strong suction of waterthrough the filter F of the present invention when the spa's circulationsystem is operated also creates a negative, or vacuum, pressure on theinside of the filter and serves to pull the sheath 22 of the filter bag20 tightly against the exterior of the filter body. Throughput isincreased through the various embodiments of the filter body (FIGS.2-4), the effect of the sheath being pulled tightly against the outsidesurface of the filter body is increased accordingly. It will be furtherappreciated that as the sheath is pulled tightly against the outsidesurface of the filter body during use, effectively, a tight fit iscreated. Therefore, all spa water passing through the auxiliary spawater inlet openings must pass through the filter bag's sheath.

[0053] The design and structure of the internal spa filter of thepresent invention provides yet another benefit for both the use and lifeof the spa. The porosity of the filter bag B material, the configurationof the pocket 22, and the vortex effect achieved through the relativelyunimpeded swirling action of the water passing through the pocket andout of the filter body cooperate to provide for much higher flow ratesthrough the filter than can be achieved by the commonly-used prior artcartridge filters. Typically, new and clean cartridge filters arecapable of flow rates on the order of 100 gallons per minute, as limitedby the material and structure of the pleated filter media. Whereas, thefilter bag B disclosed herein is capable of flow rates of more than 150gallons per minute, for a flow rate increase of approximately 50%. Itwill be appreciated by those skilled in the art that this increased flowrate translates to increased efficiency of the spa. For example, theincreased flow rate allows for a more forceful flow of water from thespa jets 80, increasing the relaxation and therapeutic benefits to theuser. Relatedly, the increased flow rate achieved through the filter ofthe present invention improves the performance and capabilities of stateof the art jet configurations involving multiple “total body” jets or“waterfalls,” for example. Moreover, because the circulation pump 28 iseffectively working against less resistance from the filter, it does nothave to work as hard to generate the increased flow rates, therebyprolonging the life of the pump.

[0054] With continued reference to FIG. 12, when the filter bag B hasbecome dirty and is to be cleaned or replaced, the spa's circulationsystem is shut down and the door 86 to the filter-receiving bay 82 isopened. The filter bag 20 may then be lifted out of the filter body FBby simply grasping the handle 38 and pulling the bag up and out of thefilter body. It will be appreciated that the debris trapped by thefilter during use will be, for the most part, contained within thefilter bag pocket. In this way, when the filter bag is removed, the riskthat any debris will fall out of the pocket and back into the spa wateror into the clean side of the circulation system is reduced as comparedto the typical prior art cartridge filter, where all debris is trappedon the outside of the filter and can easily fall off the filter and backinto the spa when the filter is removed. Moreover, because the filterbag B is capable of being removed without unscrewing and removing thesupporting filter body, the risk of loosening trapped debris and itfalling back into the spa water is further reduced because of thedecreased handling and manipulation of the filter. Aside from bettermaintaining the cleanliness of the spa water, the spa filter of thepresent invention is also more convenient to use, because of the reducedhandling and the simplicity of lifting up on the filter bag handle toclean or replace the filter bag.

[0055] Once the filter bag B is removed from the spa, the bag may simplybe dumped or rinsed out to remove all debris that has been trapped.Further, because of the structure and materials of the filter bag, thefilter bag may also be washed or laundered in a conventional washingmachine and dryer to more thoroughly clean and sanitize the bag. As isknown in the art, to further sterilize the filter bag and chemicallybreak down and remove any suntan lotions and other oils, calcificationbuild-up, and the like, the bag may be soaked in a cleaning solutionmade up of water and an active ingredient such as tri-sodium phosphateor muriatic acid. If the filter bag has been in use for many months oris otherwise showing wear or other effects of use, making cleaning andreuse of the bag less optimal, the bag may be simply discarded and a newbag put into use. It will be appreciated that the materials andconstruction methods themselves employed in producing the filter of thepresent invention are known in the art and are relatively inexpensive,causing disposability of the filter bag to be a convenient andeconomical option in the user's ongoing spa maintenance program.

[0056] While embodiments of the invention have been illustrated anddescribed, it will be apparent that various modifications can be madewithout departing from the spirit and scope of the invention.Accordingly, it is not intended that the invention be limited, except asby the appended claims.

What is claimed is:
 1. An internal filter for connecting water from aspa to the suction end of a spa water circulation system, said filtercomprising: a filter body that includes a cylinder having a spa waterinlet opening at one end and a spa water discharge orifice at itsopposite end, the sides of such cylinder being formed with auxiliary spawater inlet openings; a filter bag that includes a cylindrical sheathwhich extends from the rear end of the filter body encompassing theexterior of the filter body, such filter bag also being formed with apocket that extends concentrically inwardly from the front end of thesheath rearwardly into the filter body from the main spa water inletopening; and water connection means between the filter bag dischargeopening and the suction end of the spa water circulation system wherebyupon operation of the spa water circulation system spa water is drawninto the main spa water inlet opening and through the filter bag pocketinto the interior of the filter body while concurrently spa water isdrawn transversely through the filter bag sheath and auxiliary spa wateropenings into the confines of the filter body, with all of such spawater flowing rearwardly and then out of the filter body through thefilter body discharge orifice.
 2. An internal spa filter as set forth inclaim 1 which further includes a handle on the filter bag for removingthe filter bag from the confines of the filter body.
 3. An internal spafilter as set forth in claim 1 wherein the auxiliary spa water inletopenings are holes.
 4. An internal spa filter as set forth in claim 1wherein the auxiliary spa water inlet openings are of a mesh-typeconstruction.
 5. An internal spa filter as set forth in claim 1 whereinthe auxiliary spa water inlet openings are a plurality of axiallyextending slots.
 6. An internal spa filter as set forth in claim 1wherein the filter body discharge orifice is smaller than the filterbody spa water inlet opening whereby spa water flowing through thefilter body forms a vortex that traps debris which is too large to passthrough the filter bag pocket within the pocket.
 7. An internal spafilter as set forth in claim 1 which further includes a support ringwhich is attached to the sheath to abut the end of the filter bodyadjacent the spa water inlet opening of such filter body.
 8. An internalspa filter as set forth in claim 2 wherein the filter body dischargeorifice is smaller than the filter body spa water inlet opening wherebyspa water flowing through the filter body forms a vortex that trapsdebris which is too large to pass through the filter bag pocket withinthe pocket.
 9. An internal spa filter as set forth in claim 2 whichfurther includes a support ring which is attached to the sheath to abutthe end of the filter body adjacent the spa water inlet opening of suchfilter body.
 10. An internal filter for connecting water from a spa tothe suction end of a spa water circulation system, said filtercomprising: a filter body that includes a vertically extending cylinderhaving a spa water inlet opening at its upper end and a spa waterdischarge orifice at its lower end, the sides of such cylinder beingformed with auxiliary spa water inlet openings; a filter bag having acylindrical sheath which extends upwardly from the lower end of thefilter body to the upper end of such filter body, the sheathencompassing the exterior of the filter body, such filter bag also beingformed with a pocket that extends concentrically downwardly from theupper end of the sheath downwardly into the filter body from the mainspa water inlet opening; and water connection means between the filterbag discharge orifice and the suction end of the spa water circulationsystem whereby upon operation of the spa water circulation system spawater is drawn downwardly into the main spa water inlet opening andthrough the filter bag pocket into the interior of the filter body whileconcurrently spa water is drawn transversely through the filter bagsheath and auxiliary spa water openings into the confines of the filterbody, with all of such spa water flowing downwardly out of the filterbody through the filter body discharge orifice.
 11. An internal spafilter as set forth in claim 10 which further includes a handle on thefilter bag for removing the filter bag from the confines of the filterbody.
 12. An internal spa filter as set forth in claim 10 wherein theauxiliary spa water inlet openings are holes.
 13. An internal spa filteras set forth in claim 10 wherein the auxiliary spa water inlet openingsare of a mesh-type construction.
 14. An internal spa filter as set forthin claim 10 wherein the auxiliary spa water inlet openings are aplurality of axially extending slots.
 15. An internal spa filter as setforth in claim 10 wherein the filter body discharge orifice is smallerthan the filter body spa water inlet opening whereby spa water flowingthrough the filter body forms a vortex that traps debris which is toolarge to pass through the filter bag pocket within the pocket.
 16. Aninternal spa filter as set forth in claim 11 which further includes asupport ring attached to the sheath to abut the end of the filter bodyadjacent the spa water inlet opening of such filter body.
 17. A spaconstruction, comprising: a tub having water discharge jets; a spa watercirculation system that includes a pump; a filter-receiving bay incommunication with said tub; a filter body that includes a verticallyextending cylinder having a spa water inlet opening at its upper end anda spa water discharge orifice at its lower end, the sides of suchcylinder being formed with auxiliary spa water inlet openings; a filterbag having a cylindrical sheath which extends upwardly from the lowerend of the filter body to the upper end of such filter body, the sheathencompassing the exterior of the filter body, such filter bag also beingformed with a pocket that extends concentrically downwardly from theupper end of the sheath downwardly into the filter body from the mainspa water inlet; and piping disposed between the filter body dischargeopening and the suction end of the pump and between the discharge end ofthe pump and the tub water discharge jets whereby upon operation of thepump spa water is drawn from said tub into said bay and then downwardlyinto the main spa water inlet opening and through the filter bag pocketinto the interior of the filter body while concurrently spa water isdrawn transversely through the filter bag sheath and auxiliary spa wateropenings into the confines of the filter body, with all of such spawater flowing downwardly out of the filter body through the filter bodydischarge orifice and through the water discharge jets back into thetub.
 18. A spa construction as set forth in claim 17 which furtherincludes a handle on the filter bag for removing the filter bag from theconfines of the filter body and out of the filter-receiving bay.
 19. Aspa construction as set forth in claim 17 wherein the filter bodydischarge orifice is smaller than the filter body spa water inletopening whereby spa water flowing through the filter body forms a vortexwithin the pocket that traps debris which is too large to pass throughthe filter bag.
 20. A spa construction as set forth in claim 17 whereinthe filter bag further includes a support ring to abut the end of thefilter body adjacent the spa water inlet opening of the filter body. 21.A method of filtering debris from water contained in a spa, the spahaving a spa water circulation system that includes a suction inlet,said method including the steps of: providing a filter body thatincludes a cylinder having a spa water inlet opening at one end and aspa water discharge orifice at its opposite end, the sides of suchcylinder being formed with auxiliary spa water inlet openings; providinga filter bag having a cylindrical sheath that encompasses the exteriorof the filter body and a coaxial pocket that extends into the filterbody from the spa water inlet openings; and connecting the filer bodydischarge orifice to the suction inlet of the spa water circulationsystem whereby upon operation of the spa water circulation system wateris drawn axially into the main spa water inlet and through the filterbag pocket into the interior of the filter body, while concurrentlywater is drawn transversely through the filter bag sheath and auxiliaryspa water openings into the confines of the filter body, with all ofsuch spa water flowing through the filter bag and then out of the filterbody through the filter body discharge orifice.
 22. A method as setforth in claim 21 wherein the filter body discharge orifice is formedsmaller than the filter body spa water inlet opening whereby spa waterflowing through the filter body creates a vortex that traps debris whichis too large to pass through the filter bag pocket within the pocket.23. A method as set forth in claim 21 which further includes providingthe filter bag with a handle and using the handle to remove the filterbag from the filter body when such filter bag is to be cleaned orreplaced.
 24. A method as set forth in claim 22 which further includesproviding the filter bag with a handle and using the handle to removethe filter bag from the filter body when such filter bag is to becleaned or replaced.